8-021 BLACK BUNA 90D BACK-UP RING

This back-up ring is supplied in AS568-021 black Buna-N (Nitrile) 90 Shore A supplied with an inside diameter of 0.926 in (23.52 mm), a cross section of 0.07 in (1.78 mm), and an outside diameter of 1.066 in (27.08 mm), catalogued under part number HB90021. It installs on the low-pressure side of an o-ring to prevent extrusion into the clearance gap at elevated pressure.

As a material, Buna-N (Nitrile) offers strong abrasion and tear resistance, the most widely specified general-purpose sealing elastomer. Expect good resistance to propane and butane, many alcohols, and greases and lubricants. Continuous operating temperature is published at -40°F (-40°C) to 250°F (121.1°C). It should not be specified for service in strong acids or ketones.

It sees regular use in construction equipment, fluid power, and general industrial maintenance.

Order part number HB90021, sold individually. Unit weight is approximately 0.176 g. Confirm chemical compatibility, pressure and temperature against your own application requirements before installing. If you need a size, durometer or compound that is not listed, APG can cross-reference from a print, a sample or a competitor part number.